The present invention relates to a resin erecting lens array that comprises at least two opposed resin lens plates on which spherical or aspherical micro-lenses are arranged at established intervals. The present invention also relates to a method for fabricating such a resin erecting lens array.
Heretofore, methods for fabricating such a kind of resin erecting lens array has been disclosed by the present inventors in Japanese Patent Application Laying-open Nos. 11-245266 (1999) and 200-30306 (2000). That is, these official publications disclose the method for manufacturing a resin lens plate and the method for fabricating a resin erecting lens array.
In FIGS. 1A to 1C, there is illustrated the method for fabricating the resin erecting lens array disclosed in the above publications. Also, in FIG. 2, there is shown a plane view of the resin lens plate.
As shown in these figures, two or more lens plates 10, 12 which are formed by an injection molding can be placed one on top of another as follows. At first, as shown in FIG. 1A, protruded portions 16 formed on the end portions of the lens plate are engaged in the respective recessed portions 14 formed on the end portions of the opposite lens plate. Then, as shown in FIG. 2B, clips 18 are fixed up on the lens plates 10, 12 from their sides, respectively, to hold the lens plates 10, 12 together as shown in FIG. 1C.
Alternatively, the lens plates may be held together not only using clips but also using an adhesive depending on the circumstances. That is, the adhesive is poured into the recessed portion 14 and then the protruded portion 16 is placed in the recessed portion 14 filled with the adhesive. Then, alignment is checked to make sure they are in proper relative position. If they are properly arranged, then a pressure is applied on the layers along the direction of fitting the protruded portion into the recessed portion such that two lens plates 10, 12 are brought into a temporary fixation. Subsequently, clips 18 are fixed up on the lens plates 10, 12 from their sides, respectively, to hold the lens plates 10, 12 together.
In the conventional method for fabricating the resin erecting lens array, however, there is a need to provide a substantially large area on the fringe of the lens plate for each clip 18 to be used for holding the plates together, while micro-lenses cannot be arranged on such an area. Therefore, there is a problem in that the whole size of a device becomes large. In addition, there is another problem that the lens plates go out of alignment by vibrations.
For solving such problems, there is an idea of using only an adhesive but not clips to hold the lens plates together. In this case, however, an additional problem may be arisen with respect to an adhesive strength between the flat resin surfaces. Moreover, if the adhesion area is made small, the adhesive strength between the lens plates decrease. Therefore, there is caused a further problem where the reliability of the resin erecting lens array decreases.
An object of the present invention is to provide a novel method for fabricating a resin erecting lens array, which includes means of solving the above problems.
Another object of the present invention is to provide a novel resin erecting lens array, which can be fabricated by such a method.
A further object of the present invention is to provide a resin lens plate to be used in the resin erecting lens array.
In the first aspect of the present invention, a method for fabricating a resin erecting lens array constructed of two or more resin lens plates being placed on top of one another, where each of resin lens plate is formed by an injection molding and is provided as a plate on which spherical or aspherical micro-lenses are arranged at established intervals, comprises the steps of: forming an aperture stop for a spherical or aspherical surface of each lens on the surface of the resin lens plate; applying an adhesive on protruded portions and in recessed portions formed on the end portions of the resin lens plate; spreading out the adhesive into the space between the adjacent resin lens plates; aligning an optical axis of each lens of the two or more resin lens plates; and hardening the adhesive.
In the second aspect of the present invention, a method for fabricating a resin erecting lens array constructed of two or more resin lens plates being placed on top of one another, where each of resin lens plate is formed by an injection molding and is provided as a plate on which spherical or aspherical micro-lenses are arranged at established intervals, comprises the steps of: forming an aperture stop for a spherical or aspherical surface of each lens on the surface of the resin lens plate; applying an adhesive on protruded portions and in recessed portions formed on the end portions of the resin lens plate; spreading out the adhesive into the space between the adjacent resin lens plates; aligning an optical axis of each lens of the two or more resin lens plates; hardening the adhesive; and inserting heat-melting resin pins into the pin-insert holes of the resin lens plates, which are formed in the predetermined positions on the end portions of the resin lens plate, and melting at least one end of each resin pin.
In the third aspect of the present invention, a method for fabricating a resin erecting lens array constructed of two or more resin lens plates being placed on top of one another, where each of resin lens plate is formed by an injection molding and is provided as a plate on which spherical or aspherical micro-lenses are arranged at established intervals, comprises the steps of: forming an aperture stop for a spherical or aspherical surface of each lens on the surface of the resin lens plate; aligning an optical axis of each lens of the two or more resin lens plates; and inserting heat-melting resin pins into the pin-insert holes of the resin lens plates, which are formed in the predetermined positions on the end portions of the resin lens plate, and melting at least one end of each resin pin.
In the fourth aspect of the present invention, a resin lens plate formed by an injection molding, where spherical or aspherical micro-lenses are arranged on a plate at established intervals, comprises: pin-insert holes are formed in end portions through which heat-melting resin pins can be inserted for mechanically securing two or more resin lens plates together, and/or recessed and protruded portions are formed on end portions for increasing the contact area of an adhesive.
In the fifth aspect of the present invention, a resin electing lens array comprises two or more resin lens plates described above which are combined together, where two or more resin lens plates are secured together using an adhesive applied on recessed and protruded portions formed on end portions of each resin lens plate, and/or are secured together using heat-melting resin pins being inserted into pin-insert holes formed at the predetermined positions of end portions of each resin lens plate.